This paper is concerned with two topics on dynamic fracture phenomena related to electromagnetic force. An edge-cracked specimen which carries a transient electric current I is simply supported in a steady magnetic field B. As a result of their interaction, the dynamic electromagnetic force occurs in the whole body of the specimen, which is then deformed to fracture in the opening mode of cracking.The first half of the paper describes three-dimensional finite element analyses of the transient electric current flowing around a crack. The magnetic vector potential method (i.e. A-Φ method) is employed to formulate the three-dimensional electromagnetic field problem. In order to deal with infinite boundary conditions in the FE analyses, an infinite element technique is utilized. The skin effects on the electric current distribution around the crack are discussed in detail.The second half describes high-strain-rate effects on fracture toughness under the dynamic electromagnetic force. To obtain the fracture toughness values, we use the electric potential and the J-R curve methods to determine the dynamic crack initiation point in the experiment, together with the finite element method to calculate the dynamic fracture parameter with high-strain-rate plasticity effects. Then, the dynamic fracture toughness values of a ferritic steel are evaluated over a wide temperature range from lower shelf to upper shelf.
Fracture mechanics behavior of a NiFe superalloy sheath for superconducting fusion magnets. Part 2. magnet life analysis model